I. Field of the Invention
The present invention relates to a system for measuring the limbus-to-limbus diameter of an eye and more specifically, to a system using laser-slit illumination of the eye for measurement of the limbal diameter and deriving an anterior chamber diameter from the limbal diameter.
II. Description of the Related Art
A common measurement for an eye care professional in fitting lenses or performing surgical procedures such as laser assisted in-situ keratomileusis (LASIK) or for inserting an inter-corneal lens (ICL) is to measure the diameter of the cornea or the limbus-to-limbus measurement. The limbus is a junction of the cornea of the eye and the sclera which extends all around the periphery of the cornea. This limbal diameter measurement is used to determine the diameter of the external boundary of the cornea and is used with LASIK surgery or contact lens fitting. This limbal diameter measurement is also used to determine the internal interior chamber diameter or angle-to-angle measurement which is critical for properly fitting an ICL in a patient""s eye.
It is known to obtain the limbal diameter measurement using what is commonly known as a Holliday disk, or a scale held near the patient""s eye, or a caliper held near the patient""s eye. None of these known techniques provide for a precise measurement of the limbal diameter.
If the calculated limbal diameter is sufficiently larger than the actual limbal diameter, it is possible that an ICL that is too large may be incorrectly inserted into the patient""s eye; thereby causing pressure to the trabecular meshwork and Schlemm""s canal. These problems could have an adverse effect on the natural aqueous flow from the eye or on the refractive outcome following ICL implantation. Conversely, a calculated limbal diameter that is too small could result in a lens that is too small for the patient""s eye. This could be problematic because the ICL could move out of place.
Therefore it is important that an easy and accurate system to measure limbal diameter be obtained.